Co2 refrigeration system for ice-playing surface

ABSTRACT

A CO 2  refrigeration system for an ice-playing surface comprises a transfer circuit, a CO 2  refrigerant circuit and an independent condensation circuit. A transfer refrigerant circulates between a condensation heat exchanger and an evaporation heat exchanger. The CO 2  circuit is in relation with the condensation heat exchanger to release heat from the CO 2  refrigerant. The CO 2  circuit comprises a CO 2  condensation reservoir and an evaporation stage to receive the CO 2  refrigerant from the condensation reservoir. The independent circuit is in relation with the refrigerant of the transfer circuit at the evaporation heat exchanger. The independent circuit comprises a magnetically operated compressor to compress a secondary refrigerant, a condensation stage and an evaporation stage in which the secondary refrigerant absorbs heat.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority on Canadian Patent Application No. 2,735,347, filed on Mar. 28, 2011 and issued to Canadian Patent No. 2,735,347 on Oct. 11, 2011, incorporated herein by reference.

FIELD OF THE APPLICATION

The present application relates to refrigeration systems used to refrigerate ice-playing surfaces such as a skating rinks, curling sheets, etc, and more particularly to refrigeration systems using CO₂ refrigerant.

BACKGROUND OF THE ART

With the growing concern for global warming, the use of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) as refrigerant has been identified as having a negative impact on the environment. These chemicals have non-negligible ozone-depletion potential and/or global-warming potential.

As alternatives to CFCs and HCFCs, ammonia, hydro-carbons and CO₂ are used as refrigerants. Although ammonia and hydrocarbons have negligible ozone-depletion potential and global-warming potential as does CO₂, these refrigerants are highly flammable and therefore represent a risk to local safety. On the other hand, CO₂ is environmentally benign and locally safe.

SUMMARY OF THE APPLICATION

It is therefore an aim of the present disclosure to provide a CO₂ refrigeration system for ice-playing surfaces that addresses issues associated with the prior art.

Therefore, in accordance with the present application, there is provided a CO₂ refrigeration system for an ice-playing surface, comprising: a transfer circuit in which a transfer refrigerant circulates between a condensation heat exchanger to absorb heat, and an evaporation heat exchanger to release heat; a CO₂ refrigerant circuit in heat-exchange relation with the condensation heat exchanger to release heat from the CO₂ refrigerant, the CO₂ refrigerant circuit comprising a condensation reservoir accumulating a portion of the CO₂ refrigerant in a liquid state and an evaporation stage receiving the CO₂ refrigerant from the condensation reservoir to absorb heat from the ice-playing surface; and an independent condensation circuit in heat-exchange relation with the transfer refrigerant of the transfer circuit at the evaporation heat exchanger, the independent condensation circuit comprising a compression stage with at. least one magnetically operated compressor to compress a secondary refrigerant, a condensation stage in which the secondary refrigerant releases heat, and an evaporation stage in which the secondary refrigerant is in heat-exchange relation with the transfer refrigerant of the transfer circuit at the evaporation heat exchanger to absorb heat therefrom.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a CO₂ refrigeration system for ice-playing surface in accordance with an embodiment of the present application.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings and more particularly to FIG. 1, there is illustrated a CO₂ refrigeration system 1 for ice-playing surface.

In FIG. 1, the CO₂ refrigeration system 1 has a CO₂ evaporation closed circuit 10, in which cycles CO₂ refrigerant. The CO₂ evaporation circuit 10 comprises a condensation reservoir 12 accumulating CO₂ refrigerant in a liquid and gaseous state.

Line 14 directs CO₂ refrigerant from the condensation reservoir 12 to an evaporation stage, with a flow of CO₂ refrigerant induced by pump and/or an expansion valve(s) as generally indicated as 15. As is shown in FIG. 1, the CO₂ refrigerant is then fed to the ice-playing surface evaporation stage 16.

The ice-playing surface evaporation stage 16 of FIG. 1 may consist of a circuit of pipes positioned under the ice-playing surface, in which the CO₂ refrigerant circulates to absorb heat from fluid being frozen to form the ice-playing surface, or to maintain the ice-playing surface frozen.

The ice-playing surface evaporation stage 16 of FIG. 1 may also consist of an evaporation exchanger, by which the CO₂ refrigerant of the evaporation circuit 10 absorbs heat from a closed circuit of pipes of the ice-playing surface refrigeration stage 16. An alternative refrigerant circulates in the closed circuit of pipes of the ice-playing surface refrigeration stage 16, such as brine, glycol, or the like.

CO₂ refrigerant exiting the evaporation stage 16 is directed to the condensation reservoir 12, by way of line 18.

The CO₂ evaporation circuit 10 is in a heat-exchange relation with a transfer circuit 20. The transfer circuit 20 is a closed circuit for instance of the type in which a transfer refrigerant (e.g., alcohol-based such as glycol, water, brine or the like) cycles. A condensation heat exchanger 21 is in fluid communication with the condensation reservoir 12, so as to receive CO₂ refrigerant in a gaseous state, whereby the transfer refrigerant absorbs heat from the CO² refrigerant in the heat exchanger 21. According to an embodiment, the condensation heat exchanger 21 has a coil that is positioned inside the condensation reservoir 12.

The condensation heat exchanger 20 cycles the transfer refrigerant between the heat exchanger 21 and an evaporation heat exchanger 31 of an independent condensation circuit 30. Although not shown, appropriate flow-inducing devices may be used, such as a pump. Accordingly, the transfer refrigerant absorbs heat from the CO₂ refrigerant circulating in the CO₂ evaporation circuit 10, and releases the heat to the refrigerant circulating in the condensation circuit 30.

The independent condensation circuit uses the heat exchanger 31 as an evaporation stage. The condensation circuit is closed and comprises a condensation refrigerant that circulates in the heat exchanger 31 so as to absorb heat from the transfer refrigerant.

In the condensation circuit, the condensation refrigerant circulates between the heat exchanger 31 in which the condensation refrigerant absorbs heat, a compression stage 32 in which the condensation refrigerant is compressed, and a condensation stage 33 in which the condensation refrigerant releases heat. The compression stage 32 may use Turbocor™ compressors, or any other appropriate magnetically operated type of compressor. In an example, the condensation stage 33 features heat reclaiming (e.g., using a heat exchanger with a heat-transfer fluid) in parallel or in series with other components of the condensation stage 33, so as to reclaim heat from the CO₂ refrigerant.

It is pointed out that the condensation circuit may be used with more than one CO₂ refrigeration circuit. In such a case, the condensation circuit features a plurality of heat exchangers 20, for instance with one for each of the CO₂ refrigeration circuits.

Examples of the condensation refrigerant are refrigerants such as R-404 and R-507, amongst numerous examples. It is observed that the condensation circuit may be confined to its own casing as illustrated in FIG. 1. Moreover, considering that the condensation circuit is preferably limited to absorbing heat from stages on a refrigeration pack (e.g., condensation reservoir 12, suction header in line 18), the condensation circuit does not contain a large volume of refrigerant when compared to the CO₂ refrigeration circuit, of a secondary refrigerant circuit defined hereinafter.

Although not fully illustrated, numerous valves are provided to control the operation of the CO₂ refrigeration system 1 as described above. Moreover, a controller ensures that the various stages of the refrigeration system 1 operate as described, for instance by having a plurality of sensors placed throughout the refrigeration system 1. Numerous other components may be added to the refrigeration system 1 (e.g., valves, tanks, pumps, compressors, pressure-relief systems, etc.), to support the configurations illustrated in FIG. 1.

It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims. 

1. A CO₂ refrigeration system for an ice-playing surface, comprising: a transfer circuit in which a transfer refrigerant circulates between a condensation heat exchanger to absorb heat, and an evaporation heat exchanger to release heat; a CO₂ refrigerant circuit in heat-exchange relation with the condensation heat exchanger to release heat from the CO₂ refrigerant, the CO₂ refrigerant circuit comprising: a condensation reservoir accumulating a portion of the CO₂ refrigerant in a liquid state; an evaporation stage receiving the CO2 refrigerant from the condensation reservoir to absorb heat from the ice-playing surface; an independent condensation circuit in heat-exchange relation with the transfer refrigerant of the transfer circuit at the evaporation heat exchanger, the independent condensation circuit comprising: a compression stage with at least one magnetically operated compressor to compress a secondary refrigerant; a condensation stage in which the secondary refrigerant releases heat; and an evaporation stage in which the secondary refrigerant is in heat-exchange relation with the transfer refrigerant of the transfer circuit at the evaporation heat exchanger to absorb heat therefrom.
 2. The CO₂ refrigeration system according to claim 1, further comprising a line extending from a top of the condensation reservoir to the heat exchanger, such that gaseous CO₂ refrigerant in the condensation reservoir is directed to the independent condensation circuit.
 3. The CO₂ refrigeration system according to claim 1, wherein the condensation heat exchanger is positioned in a line extending from the condensation reservoir to the evaporation stage.
 4. The CO₂ refrigeration system according to claim 1, wherein the condensation heat exchanger is a coil inside the condensation reservoir.
 5. The CO₂ refrigeration system according to claim 1, wherein the evaporation stage has a circuit of pipes arranged under the ice-playing surface, whereby the CO₂ refrigerant circulating in the circuit of pipes of the evaporation stage absorbs heat from the ice-playing surface.
 6. The CO₂ refrigeration system according to claim 1, wherein the evaporation stage has a heat exchanger for the heat exchange between the CO₂ refrigerant and another refrigerant circulating in a circuit of pipes arranged under the ice-playing surface, whereby the other refrigerant circulating in the circuit of pipes of the evaporation stage absorbs heat from the ice-playing surface. 